Electrically driven pump

ABSTRACT

An electrically driven pump having an electric motor designed as a disk rotor. In order to minimize the axial construction length, there is provision for arranging a magnetic ring of the disk rotor on the pump impeller. The integrated design of the motor rotor and pump impeller also makes it possible to balance the unit in one operation.

CLAIM FOR PRIORITY

[0001] This application claims priority to Application No. 10203778.7 which was filed in the German language on Jan. 30, 2002.

TECHNICAL FIELD OF THE INVENTION

[0002] The invention relates to an electrically driven pump having an electric motor designed as a disk rotor.

BACKGROUND OF THE INVENTION

[0003] In known combinations of pumps with a flanged-on electric drive, there is a large axial construction length which causes problems in specific areas of use, for example in motor vehicles. Although it is known to use disk rotors in water pumps having a low pump power, in order to reduce the axial construction length, this is not sufficient in many applications. Since the motors and the pump impellers have to be balanced separately, the assembly costs, which already are relatively high, are increased even further.

SUMMARY OF THE INVENTION

[0004] The present invention provides an electrically driven pump which, along with a minimal axial construction length, can be assembled in a simple way.

[0005] In one embodiment of the invention, there is an electrically driven pump in which a magnetic ring of the disk rotor is arranged on the pump impeller.

[0006] The invention affords the advantage that the integrated design of the pump impeller with the motor rotor gives rise to a single rotary part which can be balanced in one operation and which thereby contributes to a reduction in costs. Furthermore, by virtue of the integrated design, a considerable reduction in the axial construction length of the unit is possible, especially since there is also no need for any additional flange parts which otherwise also entail further costs. A further advantage which may be mentioned with regard to the electrically driven pump according to the invention is the possible weight saving which is advantageous particularly in use in the motor vehicle sector.

[0007] In a preferred embodiment of the invention, there is provision for the magnetic ring to be arranged in a region through which fluid flows. In such a design of the electrically driven pump as a wet rotor, the sealing-off of the rotating shaft may be dispensed with, with the result that the number of parts and the assembly costs can be further reduced. Since the seal is not necessary, this also avoids the frictional losses due to the sealing elements, which may be considerable, for example, in the case of a slide-ring seal, such as is often provided where a dry rotor is concerned. It is particularly advantageous that the magnetic ring of the electric motor designed as a disk rotor, because of its possible rotationally symmetric disk shape, does not cause any splash losses which lead to considerable losses of efficiency in conventional wet rotors having flow-around rotors of the electric motor.

[0008] In another preferred embodiment, there is provision for the stator of the electric motor to be arranged outside that region of the pump through which fluid flows, for example outside the pump casing or in a separate chamber sealed off from the region through which fluid flows, while control and/or power electronics for the electric motor may preferably also be arranged in such a chamber. In the case of such an arrangement, the current-carrying parts can be reliably separated from the fluid regions, since the casing seals necessary for this purpose are simple and permanent.

[0009] In still another preferred embodiment of the invention, there is provision for the electrically driven pump to be designed as a radial pump with a radial impeller, on the rear side of which the magnetic ring is arranged. In such an embodiment, the insignificant axial length of the magnetic ring leads to a minimal axial construction length of the radial impeller of the pump, while the stator and, if appropriate, the electronics can be accommodated, so as to save space axially, in the region of the in any case necessary bearing elements of the pump impeller, in the chamber already referred to, radially outside the mounting.

[0010] In another embodiment, the magnetic ring of the adjacent casing wall is designed as hydrodynamic friction bearings for the absorption of axial forces. In this embodiment, the magnetic gap necessarily serves as a friction bearing, a particularly space-saving hydrodynamic axial bearing being provided, which manages without any additional parts during assembly. Preferably, the shaft of the pump impeller may also be mounted in the casing by means of hydrodynamic friction bearings for absorbing the radial forces. Alternatively to a hydrodynamic design of the axial bearing, it may also be envisaged to integrate a magnetic bearing for absorbing the axial forces into the electric motor.

[0011] The electrically driven pump according to the invention may be used, in principle, in the most diverse applications and be designed correspondingly as a water pump, air-conditioning compressor, gasoline pump or hydraulic oil pump, and, because of its short axial construction length and its small number of parts, it is suitable particularly for use in the motor vehicle sector. Particularly where water pumps are concerned, it has been customary hitherto to drive these mechanically by means of the V-belt or toothed belt. The pump according to the invention possesses in this case a comparable axial construction length to a conventional water pump with a belt pulley, whereas known electrically driven water pumps in the motor vehicle sector are conventionally designed with a flanged-on electric motor and accordingly have the disadvantages mentioned initially.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] An exemplary embodiment of the invention is dealt with in more detail below with reference to the accompanying drawing, in which:

[0013]FIG. 1 shows an electrically driven water pump for use in the motor vehicle sector.

DETAILED DESCRIPTION OF THE INVENTION

[0014]FIG. 1 shows an electrically driven water pump 10 for use in the motor vehicle sector. The water pump 10 possesses a pump casing 12, a pump impeller 14 mounted rotatably in the casing 12 and designed as a radial impeller and an electric drive motor 16 designed as a disk rotor. The radial outlet 18 of the pump lies between the axial suction side 20 and the drive motor 16. The electric motor 16, designed, as already mentioned, as a disk rotor, possesses a magnetic ring 22 which is arranged directly on the rear side 24 of the pump impeller 14, the rear side being designed essentially as a radial surface. By virtue of this arrangement, the pump impeller 14 serves at the same time as a motor rotor and forms a compact unit which can be balanced in one operation. The disk-like design of the magnetic ring 22 avoids splash losses, such as would occur as a result of a separate motor rotor. Since the magnetic ring is arranged in the region through which fluid flows, the pump operates as a wet rotor and there is no need, between components rotated relative to one another, to have any shaft seal which would cause frictional losses and costs. The sealing-off of the entire unit is achieved solely by the casing 12 being sealed off, this being easily possible in a permanent way.

[0015] The stator 26 of the disk rotor 16 is seated in a chamber 28 which is sealed off from the region through which fluid flows and which has an annular design on the rear side of the pump impeller 14. An intermediate wall 30 of the pump casing 12 with a radial extent in this case separates the fluid region from the chamber 28. Furthermore, the chamber 28 receives control and power electronics 32 for the electric motor 16. The chamber 28 extends annularly around a bearing region 34 of the casing, rolling or preferably friction bearings 38 for absorbing the radial forces being provided between a shaft 36 of the pump impeller 14 and an annular axial wall forming the bearing region 34 of the casing 12. To avoid axial bearings with a high axial space requirement, the magnetic ring 24 and the adjacent intermediate wall 30 are designed such that, in the magnetic gap, a hydrodynamic friction bearing is obtained, which supports the axial forces of the pump impeller 14 over a large area on the intermediate wall 30 of the casing 12. Alternatively, instead of a hydrodynamic friction bearing, a magnetic bearing for absorbing the axial forces, which is integrated into the electric motor 16, may be envisaged.

[0016] In addition to the exemplary embodiment of an electrically driven water pump, as shown, the illustrated pump concept, with an electric motor designed as a disk rotor, may also be used in other pumps, for example in an air-conditioning compressor, a gasoline pump or an oil pump, for example for the hydraulic oil of a power-steering pump or in an electrohydraulic brake. Owing to the highly space-saving small axial construction length, the pump illustrated is particularly suitable for use in motor vehicles, but other applications may also be envisaged. The illustrated concept of an integrated unit includes the motor rotor and of the impeller can also be used, in principle, in turbines, in which case the magnetic ring can be seated correspondingly at a suitable point of a turbine wheel and cooperates with the stationary stator of a generator. In such an application, the same advantages as in an electrically driven pump apply in principle. 

What is claimed is:
 1. An electrically driven pump with an electric motor designed as a disk rotor, wherein a magnetic ring of the disk rotor is arranged on the pump impeller.
 2. The pump as claimed in claim 1, wherein the magnetic ring is arranged in a region through which fluid flows.
 3. The pump as claimed in claim 1, wherein a stator of the electric motor is arranged outside a region of the pump through which fluid flows.
 4. The pump as claimed in claim 3, wherein the stator is arranged outside a pump casing.
 5. The pump as claimed in claim 3, wherein the stator is arranged in a separate chamber sealed off from the region through which fluid flows.
 6. The pump as claimed in claim 5, wherein control and/or power electronics for the electric motor are arranged in the chamber.
 7. The pump as claimed in claim 1, wherein the pump is designed as a radial pump with a radial impeller, on a rear side of which the magnetic ring is formed.
 8. The pump as claimed in claim 1, wherein the magnetic ring and an adjacent casing wall are designed as a hydrodynamic friction bearing for absorption of axial forces.
 9. The pump as claimed in claim 1, further comprising a magnetic bearing for absorbing axial forces is integrated in the electric motor.
 10. The pump as claimed in claim 1, wherein the pump impeller is mounted in a pump casing by friction bearings for absorption of radial forces.
 11. The pump as claimed in claim 1, wherein the pump is designed as a water pump, air-conditioning compressor, gasoline pump or oil pump.
 12. The pump as claimed in claim 2, wherein a stator of the electric motor is arranged outside a region of the pump through which fluid flows. 